What is the relationship of kilowatt hour to energy usage?

The correct choice, which indicates that a kilowatt hour is a measure of energy consumption over time, accurately reflects the definition and significance of this unit. A kilowatt hour (kWh) quantifies the amount of energy consumed when a device with a power rating of one kilowatt operates for one hour. This measurement is essential for understanding how much electricity is used in a given period, helping both consumers and utilities track energy consumption and costs.

In practical terms, if you have a light bulb that uses 100 watts, running it for 10 hours would consume one kilowatt hour of energy (100 watts = 0.1 kilowatts x 10 hours = 1 kWh). This concept is pivotal in utility billing, where consumers are charged based on the number of kilowatt hours they use.

Understanding energy consumption over time allows consumers to make informed decisions about their energy usage and to manage their consumption more effectively, ultimately leading to energy conservation and efficiency efforts.